Shoppers enter an Urban Outfitters store at the Cherry Creek Shopping Center in Denver in… more

Photographer: Matthew Staver/Bloomberg

Millennials are starting to approach the age where they start to become nostalgic.

As digital technology advances at rapid rates and the economy continues to present challenges, millennials are beginning to long for the “good old days” of their childhood. The toys they grew up with, such as the Nintendo 64, are already classified as vintage. Even the iPhone 2Gs they were using a few years ago have now become a part of the past.

Shoppers enter an Urban Outfitters store at the Cherry Creek Shopping Center in Denver in… more

Photographer: Matthew Staver/Bloomberg

Now is the perfect time for brands to chime in and remind millennials of the good times. This can be achieved through a phrase dubbed “nostalgia marketing.” In times of instability or uncertainty, we tend to look back at happier, more simple times. For millennials, these happy and simple times are more than likely to be spawned by anything related to the decade of their youth — the 90s.

Nostalgia marketing can create an opportunity for generational inside jokes, and it can make people feel like they are kids all over again. Many brands have already caught on to the trend. By positioning their products or services in a nostalgic context, companies link themselves with happier times in the minds of millennial consumers.

Below are three examples of brands that have implemented this strategy.

1. Urban Outfitters and Lisa Frank

Urban Outfitters embraced nostalgic marketing by bringing back iconic Lisa Frank products that were once popular with young girls in the 90s. In 2012, Urban Outfitters began selling limited edition Lisa Frank stickers, folders and stationary. It even launched a Lisa Frank Contest that asked social media followers to use the hashtag, #UOxLisaFrank and create their own Lisa Frank-inspired doodle.

2. Nickelodeon

Nickelodeon is notorious for shows geared toward children and teenagers. The network created a programming block during TeenNick called “ The90s are All That.” Each night, viewers of the millennial age range could tune in to shows that were once the emblem of their childhood. The program earned the network a 50 percent ratings spike among viewers 18 to 35 years old.

3. Pepsi

Pepsi launched a new line of soft drinks called Pepsi Throwback, named because the drink is flavored with beet sugar rather than high fructose corn syrup, as it used to be. Pepsi Throwback teamed up with Atari to create a contest in which participants could play Atari Arcade games on Pepsi Throwback’s Facebook page for a chance to win an Atari Flashback console.

By finding the best qualities of an original product and then tweaking them to fit today’s mold, brands can not only bring back good times, but they can also enhance millennials’ brand association.

Lauren Katz contributed to this post.

Jeff Fromm is president of FutureCast, a millennial trends consulting firm. He also is lead editor of www.millennialmarketing.com and co-author of the book "Marketing to Millennials: Reach The Largest & Most Influential Generation of Consumers Ever." #viewsaremine.